Solitary graminoid herb growing in tussocks or dense stands due to horizontal, branched rhizomes with very short branches (0.5–2 cm). Base of tussocks densely covered by abundant, 3–5 mm broad, withered leaves and sheaths from previous years, with distinct veins, often shiny, dark to medium greyish brown. Culms several from each tussock, rarely single, 1–10(12) cm, stiffly erect, terete, glabrous, bluish green or often purplish tinged. Leaves mainly basal; culms with 1(2) leaves, mostly on the lower half of the culm.
Leaves flat or weakly canaliculate (especially in apex). Basal leaves 1–6(8) cm long, 3–5 mm broad, gradually tapering in upper half, with more or less distinct mid vein and several indistinct lateral veins, margins indistinctly serrate, glabrous, bluish green or tinged with purple.
Inflorescence of 1, rarely 2–3, cymose, usually dense heads (but see f. nana in Comments), each with numerous flowers. Heads more or less globose, 5–10 × 5–10 mm, black. Inflorescence subtended by a narrow bract with 4–6 mm long and 1.5–2 mm broad red to reddish brown sheath and a narrow to subulate blade 4–10 mm long, often extending a small distance beyond the head. Additional bracts smaller, reduced to brown sheaths hyaline at apex, glabrous. Bracteoles 2–3 mm, broadly ovate, acute, blackish and hyaline brown.
Flowers radially symmetric with 6 (3 + 3) tepals. Tepals subequal, 1.0–1.4 mm, oblong, obtuse, blackish with a paler, more or less hyaline tip. Stamens 6. Gynoecioum of 3 carpels with 3 stigmas.
Fruit a one-roomed capsule with 3 seeds. Capsule ovoid or ellipsoid, subacute to obtuse, with a very short style, shiny blackish brown. Seeds 1.0–1.2 mm, without a distinct elaiosome (see L. arcuata).
Sexual reproduction by seeds; very local vegetative reproduction as some fragmentation of tussocks may take place. Wind pollinated. Seeds are produced regularly. They germinate to 26–27 % in an experiment (Alsos et al. 2013).
Seeds are small but without any special adaptation to dispersal. Dispersal is ballistic (stiff culms) and passive, possibly mainly by strong winds.
Luzula nivalis is similar to L. confusa but differs in the following characters: In L. nivalis leaves are much broader, nearly flat and with a bluish green colour, the tepals are short (1.5–1.7 mm), and the bracts are entire and glabrous; in L. confusa the leaves are very narrow, more or less involute or canaliculate leaves with a reddish or brownish green colour, the tepals are longer (2.3–3.0 mm), and the bracts are fringed and hairy (also in L. arcuata).
Moist heaths, frost patterned ground, shallow mires, often in moss carpets, usually on fine-grained substrates with good water retention capacity. Luzula nivalis is most common on substrates with a circumneutral to basic soil reaction (pH) and avoids the regions with acidic bedrock, e.g., almost all areas in Spitsbergen south of Van Keulenfjorden and the west coast except for the Kongsfjorden area.
Present in all zones and sections. Common on many parts of Spitsbergen, some parts of Nordaustlandet, and probably also on Edgeøya, Barentsøya, and Prins Karls Forland. There are many records from Kong Karls Land but none from Hopen or Bjørnøya.
The global range is arctic circumpolar with only small extensions into mountains of the boreal zones, in Europe south to S Norway (an isolated part area).
Scholander described a forma, f. nana Schol., from Nordaustlandet (Scholander 1934: 56), as a compact, dwarf plant (1–2.5 cm tall) with culms as long as the leaves (much longer in the main form) and a much more loose inflorescence (always compact in the main form). He mentioned the plant from Torellneset and Rundhaugen (Gustav Adolf Land) and Westmanbukta (Gustav V Land). It has since been found in more places on Nordaustlandet in Gustav V Land (Kinnvika, Lindhagenbukta, near Cape Hansteen in Brennevinsfjorden, Martensøya in Sjuøyane), on Kong Karls Land (Mohnhøgda), Edgeøya (south of Habenichtbukta), and on the north coast of Spitsbergen in Ny-Friesland (Mosselbukta). Plants with a similar morphology are known from N Greenland and N Canada. Scholander noted that "every transition to the main form is seen, but it is so characteristic that it may well deserve a form-name". We have therefore mapped it separately, in wait for a more thorough study.
Luzula nivalis is found under the name L. arctica Blytt 1861 in very many treatments (e.g., Chrtek & Krísa 1980; Elven in Lid & Lid 1994; Rønning 1996; Elven & Elvebakk 1996; Cody 1996; Swab 2000). That usage has its background in Hylander (1945) who argued that the earlier name L. nivalis Sprengel 1825 refers to another (Central European) species. However, Sprengel based his name on Laestadius' name L. campestris var. nivalis, referring to plants Laestadius collected in N Sweden, and clearly belonging to our species. Kirschner (2001) designated a lectotype for Laestadius' name and finished this discussion. Luzula nivalis is the correct, priority name and has been the one in common use since 1998 (except for Swab 2000).
Alsos, I.G., Müller, E. & Eidesen, P.B. 2013. Germinating seeds or bulbils in 87 of 113 tested Arctic species indicate potential for ex situ seed bank storage. – Polar Biology 36: 819–830. Doi 10.1007/s00300-013-1307-7.
Chrtek, J. & Krísa, B. 1980. Luzula DC. – In: Tutin, T.G. et al. (eds.), Flora Europaea. 5. Alismataceae to Orchidaceae (Monocotyledones): 111–116.
Cody, W.J. 1996. Flora of the Yukon Territory. – NCR Research Press, Ottawa.
Elven, R. & Elvebakk, A. 1996. Part 1. Vascular plants. – In: Elvebakk, A. & Prestrud, P. (eds.), A catalogue of Svalbard plants, fungi, algae, and cyanobacteria. – Norsk Polarinstitutts Skrifter 198: 9–55.
Hylander, N. 1945. Nomenklatorische und systematische Studien über nordische Gefässpflanzen. – Uppsala Universitets Årsskrift 1945(7). 337 pp.
Kirschner, J. 2001. (1507–1507) Proposals to reject the names Juncus cymosus, J. radicans, Luzula capillaris, L. hyperborea, L. interrupta, and Rostkovia brevifolia (Juncaceae). – Taxon 50: 1193–1197.
Lid, J. & Lid, D.T. 1994. Norsk flora. Ed. 6 by R. Elven. – Det Norske Samlaget, Oslo.
Rønning, O.I. 1996. Svalbards flora. Ed. 3. – Norsk Polarinstitutt, Oslo.
Scholander, P.F. 1934. Vascular plants from northern Svalbard with remarks on the vegetation in North-East Land. – Skrifter om Svalbard og Ishavet 62. 155 pp.
Swab, J.C. 2000. Luzula de Candolle. – In: Flora of North America Editorial Committee (eds.), Flora of North America north of Mexico. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae: 255–267.